class_docstr: NameManager to do automatic naming.
  
  Developers can also inherit from this class to change naming behavior.
code: def __enter__(self):
      # Token can't be pickled and Token.old_value is Token.MISSING if _current.get() uses default value
      self._old_manager = _current.get()
      _current.set(self)
      return self
  
file_path: mxnet/python/mxnet/name.py
imports: import contextvars
label_desc: Use image node_id 3 for calling the NameManager obj's underlying member method code with example usage: obj.__enter__() and returns: self